function s1_generate_a_series_of_files(){
    for i in {1..100};do echo $i>/tmp/new_file$i;done
}
function s2_list_4_files_in_long_format_about_account_and_group(){
    ls -l /etc/{passwd,shadow,group,gshadow} |sort
}
function s3_find_items_related_to_given_username(){
grep -h $1 /etc{passwd,shadow} |sort -d
}
function s4_find_items_related_to_given_group_name(){
grep -h $1 /etc/{group,gshadow} |sort -d
}
function s5_create_groups_for_given_group_names(){
groupadd rnd && groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required(){
useradd -G rnd adam && useradd -G rnd bob && useradd -G itoperation calvin && useradd -G itoperation david && useradd -G rnd edward
}
function s7_change_users_shell(){
usermod -s /usr/bin/sh adam && usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy(){
passwd -n 10 -x 60 10 adam
passwd -n 10 -x 60 10 bob
passwd -n 10 -x 60 10 david
passwd -n 10 -x 60 10 calvin
passwd -n 10 -x 60 10 edward
}
function s9_set_password_for_five_users(){
local usernames=("adam""bob""calvin""david""edward")
local passwards=("$1""$2""$3""$4""$5")
if [ "${#usernames[@]}" -ne "${#passwords[@]}" ];then
echo "Error: The number of usernames and passwords must match."
return 1
fi
for ((i=0;i<${#usernames[@]};i++));do
echo "${usernames[$i]}:${passwords[$i]}"| chpasswd
done
}
function s10_lock_bobs_password(){
    usermod -L bob
}
function s11_include_adam_into_wheel_group(){
usermod -a -G wheel adam
}
function s12_change_files_permission(){
local file_index
for file_index in {1.33};do
        chmod -R 640 /tmp/new_file&((file_index * 3))
done
}
